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Bolocam
- Bolocam is a 144 element bolometer camera used at the Caltech Submillimeter Observatory, a 10.4m diameter telescope on Mauna Kea in Hawai'i. The camera can operate at either 2.1, 1.4, or 1.1mm, and is being used to study several widely varying areas of astrophysics: clusters of galaxies, the cosmic microwave background, high redshift dusty galaxies, and various galactic sources including protostars.
- We detect clusters of galaxies using the Sunyaev Zel'Dovich effect, secondary anisotropies in the cosmic microwave background. Since the magnitude of the SZ effect does not depend on redshift, in a blind survey for clusters we can detect all clusters above our mass limit out to all redshifts. This survey was started during our most recent run at the telescope, and we hope to use it to put limits on the number density of clusters, and through that put limits on the cosmological parameters. Bolocam can also observe at 1.4mm, which is the null of the thermal SZ effect, giving us the opportunity to observe the kinetic SZ effect. The kinetic SZ effect arises from the peculiar motion of the cluster with respect to the cosmic microwave background. A measurement of the kinetic SZ effect for nearby clusters can give us a map of the mass distribution of the nearby universe. Bolocam can also measure the primary anisotropies in the cosmic microwave background. Because at its lowest frequency it has a resolution of ~1 arcmin, and a field of view of 8 arcmins, Bolocam is positioned at the high ell end of the CMB power spectrum. At this angular resolution range primary anisotropies are predicted to be overwhelmed by power from large scale SZ structure, including filiments between clusters of galaxies. Bolocam will be one of the first instruments to explore this range of the power spectrum.
- Observing at 1.1mm Bolocam can detect high redshift dusty galaxies. The radiation from these galaxies is absorbed by the dust, and re-emitted at IR wavelengths. The IR radiation is then redshifted down into our 1.1mm band for galaxies at high redshift. Because of our large field of view compared with most submm instruments Bolocam has a high mapping speed. We plan to map large areas of sky to look for these high redshift galaxies, to collect a statistically significant sample we can follow up at other wavelengths to characterize more specifically. This work will help chart the star formation history of the universe, and the AGN contribution at high redshift.
- Bolocam's high mapping speed make it a natural choice for large survey's within the galaxy. We are planning a survey of star forming regions to detect young cold protostars. Protostars are shrouded with dust, and cold protostars (30K) emit in the mm wavelengths. Bolocam should be able to cover large star forming regions quickly, and produce a large data set that can be used for follow up observations.
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